Physics, Chemistry and Biology: Post your doubts here!

[Mustafa omar]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s11_qp_31.pdf please answer fast
Q 1 b , c , d) i ,
2 b , c
And question 3 all please
Am having big problem
And wer me fast plz

 

[kainat husain]

peak to peak distance means the distance from top to bottom (each peak is the amplitude), so if they want to reduce the peak to peak distance the want to reduce the height of the waveform, so the y-gain should be increased

but by this information i understood tht peak to peak mean horizontal? :/ not from peak to bottom pls have a look

 

[*MK*skydiver :D]

Funnily enough I just explained this to a friend, let me copy it

i) When its light in the dark room, the resistance of the LDR will be low, so R and thus A will have a higher share of voltage and thus be 1 (high)
When it's dark, the resistance of the LDR will be high, so R and A will have a lower share of voltage and thus be 0 (low)
ii)

That's what I think at least, and it agrees with paper mark scheme. Note that it stops at the transistor since the logic gate is off and transistor is too
EDIT: Was that the only thing you had a problem with or is it all of question?

I think i do get it now ..thanks !!!!!

 

[tribianni]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w09_qp_31.pdf Q10....c,d,e ASAP

 

[ZainH]

is it important to learn all those stupid logic gates? :\

There really EASY.
For AND gates, just remember the word "AND" .. so it means that inputs A "AND" B should be high for an high output.
NAND gates are the opposite of "AND" gates.

OR gates , just remember the word "OR" .. meaning input A "OR" B should be high for an high output.
NOR gates are the opposite of "OR" gates.

And last but not least, "NOT" gates. Just think of it like, whatever input you give it.. it says "NOT" and gives you the opposite xD.

Thats how I remembered the truth tables for the logic gates x)

 

[ZainH]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w09_qp_31.pdf Q10....c,d,e ASAP

You asked this before , and I answered. Maybe you didn't see it , so I'll just copy/paste it. Here:
For c) Use the equation for power, but you'll have to change it a bit.

Power = energy /time
Energy = power*time
Energy = current*voltage*time
Energy = current^2*resistance*time

NOW you can calcuate it as you have the current, resistance, and time!

ENergy = 2.5^2*3*1
=18.75J

For d) it's easier, just use the formula for power involving current and voltage.
Power= current*voltage
Voltage = power/current
Voltage= 18.75/2
=7.5v

For e) You just subtract the orignial voltage from the one you calculated in part d)!
22000-7.5=21992.5V

 

[kainat husain]

peak to peak is amplitude or horizontal distance between two peaks?

 

[Stormcry72]

but by this information i understood tht peak to peak mean horizontal? :/ not from peak to bottom pls have a look

well theres 2 types of peak to peak, peak to peak voltage and peat to peak time, but i dont think that img is correct
peak basically means a mountain top, so in that question i guess peak to peak stood for top to bottom for voltage

 

[ZainH]

peak to peak is amplitude or horizontal distance between two peaks?

I think its distance between 2 peaks, Im terrible at that time base setting/peak stuff.

 

[Moi]

girl u are a life saver thank you so so much

Glad i helped

 

[kainat husain]

well theres 2 types of peak to peak, peak to peak voltage and peat to peak time, but i dont think that img is correct
peak basically means a mountain top, so in that question i guess peak to peak stood for top to bottom for voltage

okkk!! hope i rmember tmw thnx

 

[gelato]

because it become a parallel circuit so (1/24)+(1/8)=4/24=1/6 so total resistance=6
11b) use the left hand rule with the direction of current in the opposite of the direction of radiation

Left hand? I only know about the right hand rule; either way, I still can't figure it out
And what about number 10 a) and b).
How do we draw the graph annnnd you said to increase the voltage, but they want it halved? Why is it not the other way around?
So confused...

 

[tribianni]

but yaar

You asked this before , and I answered. Maybe you didn't see it , so I'll just copy/paste it. Here:
For c) Use the equation for power, but you'll have to change it a bit.

Power = energy /time
Energy = power*time
Energy = current*voltage*time
Energy = current^2*resistance*time

NOW you can calcuate it as you have the current, resistance, and time!

ENergy = 2.5^2*3*1
=18.75J

For d) it's easier, just use the formula for power involving current and voltage.
Power= current*voltage
Voltage = power/current
Voltage= 18.75/2
=7.5v

For e) You just subtract the orignial voltage from the one you calculated in part d)!
22000-7.5=21992.5V

but there is no time in c !!!

 

[Moi]

Can someone plz explain this !! I did not get anything from it !!
The whole peek to peek thingy and time base... WHAT !! Plz explain

 

[Mystery]

can the colour of crystals determine the purity of them??

 

[tribianni]

nd answer dis also plzz http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_31.pdf Q 11...

 

[EpicLol]

You asked this before , and I answered. Maybe you didn't see it , so I'll just copy/paste it. Here:
For c) Use the equation for power, but you'll have to change it a bit.

Power = energy /time
Energy = power*time
Energy = current*voltage*time
Energy = current^2*resistance*time

NOW you can calcuate it as you have the current, resistance, and time!

ENergy = 2.5^2*3*1
=18.75J

For d) it's easier, just use the formula for power involving current and voltage.
Power= current*voltage
Voltage = power/current
Voltage= 18.75/2
=7.5v

For e) You just subtract the orignial voltage from the one you calculated in part d)!
22000-7.5=21992.5V

That cant be right...coz 18.75/2 does not equal 7.5V....

P = V^2/R so
V = (PR)^0.5
V = (18.75*3)^0.5 = 7.5V

 

[sma786]

There really EASY.
For AND gates, just remember the word "AND" .. so it means that inputs A "AND" B should be high for an high output.
NAND gates are the opposite of "AND" gates.

OR gates , just remember the word "OR" .. meaning input A "OR" B should be high for an high output.
NOR gates are the opposite of "OR" gates.

And last but not least, "NOT" gates. Just think of it like, whatever input you give it.. it says "NOT" and gives you the opposite xD.

Thats how I remembered the truth tables for the logic gates x)

Thanks alot, really helpfull

 

[EpicLol]

nd answer dis also plzz http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_31.pdf Q 11...

Look at the image that is how they should be drawn but without the wiggly bits....

 

[sma786]

Yeah, the slight chance that they do end up asking a question about those.. its usually worth alot of marks :S

they dont fit in my brain -.- lol ..